1. Field of the Invention
This invention relates to archery bows and, in particular, to a pivotal pocket for mounting a bow limb on a handle.
2. Description of the Prior Art
There are a number of different archery bow configurations, the more traditional forms of which include the English long bow, the Turkish Recurve and the American Indian Flat bow. Other more modern bows include the one-piece and take-apart recurve bow. The most recent such bow is the highly popular compound bow. In all of these bow designs, the archer pulls the bow string which, in turn, flexes the bow limbs to temporarily store energy. When the archer releases the bow string, the bow limbs return to their original position, thus taking up the bow string and transferring the energy from the bow limbs through the bow string to the arrow.
Unlike the traditional bows of the past that were made in one piece, most modern bows are made up of separate handle and limb units that are mechanically assembled to form the bow. While the present invention refers to the attachment of flexible limbs to the handles of compound bows, it may also be used with the modern take-apart or take-down recurve bows.
Compound bows differ from traditional bows in that they utilize a variable leverage system at the limb tips to provide a system that is capable of storing more energy for a given draw length. The mechanical advantage provided by the variable leverage system also allows the archer to hold the bow at full draw with much less effort so that aiming the bow is accomplished with less strain. While the compound bow variable leverage system reduces the strain placed on the archer, it increases the mechanical operating stress and strain on individual bow components. For that reason, compound bows require considerably stiffer limbs for a given bow draw weight than do traditional bows. The stiffer limbs apply greater loads and bending moments to the bow handle and therefore the connection between the limb and handle must be strong and positive. It is further desirable that the resistance provided by the limbs be adjustable over a predetermined range of bow draw weights.
The prior art, such as U.S. Pat. No. 4,261,320, provides for adjustably attaching the bow limbs by means of a pivot at each end of the handle of a compound bow. The pivot consists of a semicircular groove in each end of the handle which is perpendicular to the length of the handle. Each limb is fitted with a half round member having a flat side and a curved side. The flat side of the half round member fits against the limb near the fixed end, and the curved side is mated to a semicircular groove in the handle end. The side walls of the handle also form the side walls of the limb pocket. The patent further discloses a second method of pivotally attaching bow limbs to a handle in which the male pivot portion is part of or affixed to each end of the bow handle. The other end of a limb pivot plate is fitted with a threaded means to adjustably attach it to the bow handle. Both methods require that the bow handle be of a hollowed out configuration in the area of limb attachment and thus have limited, if any, applicability to the relatively narrow solid metal bow handles presently in use.
More recent prior art relating to the pivotal attachment of the bow's limbs to the handle include U.S. Pat. No. 3,486,495; U.S. Pat. No. 3,957,027; U.S. Pat. No. 3,958,551; U.S. Pat. No. 4,064,862 and U.S. Pat. No. 5,280,779.